Comprehensive study of garlic peel extract coating against mild steel corrosion in saline medium

Natural materials (NMs) have emerged as better alternatives for the mitigation of corrosion of metals. NMs can be used as both inhibitors and coatings; however, they have been used mostly as inhibitors. In this work, ethanol extract of garlic peel (EEGP) has been synthesized and investigated by Fourier transform infrared (FT-IR) and UV-visible spectroscopy (UVS). The results have confirmed that biomolecules are present in the prepared extract. EEGP has been coated on mild steel (MS) by drop casting (DC) in layers (one and two). The coated MS have been examined in 0.5 M NaCl by open circuit potential (OCP) and potentiodynamic polarization (PDP) measurements. The results have shown that EEGP protect MS in 0.5 M NaCl with the maximum efficiency of 71%. The conditions of bare, coated, and corroded MS have been visually monitored through camera images and atomic force microscopy (AFM), which advocates that EEGP protect MS. Based on the results, a schematic for corrosion prevention of MS by EEGP coatings has also been proposed.